Shock Sensor Question

[Igor Dorrestijn]

> The strain gauge sounds interesting though.  Curious of how I could apply
> strain gauges to measure wheelie bar Hit?  Any ideas?  The question is
where
> should it be attached.  Are they always attached to a coil/spring or can
you
> actually bond it to a metal bar and measure the bend, basically when the
> wheelie bars hit the ground, the bars may flex some, this way we could
tell
> which bar is hitting harder.  How about calibrating this, any ideas?  The
> only other concern is position of the sensor, if you bond a stain device
to
> the bottom of the bar assuming it will flex up, when we adjust the whellie
> bars, we rotate the bar (on a bolt) to adjust in or out.  Any time the
bars
> are turned, the sensor will rotate.  Wont be easy to implement and make it
> functional so that it allows for changing the position of the bars.
>
> Steve

In theory it should work something like this: you put two strain gauges on
opposite sides of the bar. By measuring the difference between the two you
measure bending. If you add the two signals you measure compression. You can
still measure the compression with only one strain gauge if the bar doesn't
bend much.
All this adding and subtraction is after your wheatstone bridges and
differential amplifiers of course.
If you want calibrated values use strain gauges with two perpendicular
gauges on the same sensor so you can easily compensate for temperature
drift, especially with the semiconductor versions.
Mounting strain gauges also seems to be an art in itself, the manufacturer
should have usefull opinions on this.
And finally a disclaimer: I haven't tried this myself so don't take it too
seriously.

Igor


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